Exhaust muffler with expansion chamber



Nov. 24, 1953 v G. B. WALKER 2,660,256

EXHAUST MUFFLER WITH EXPANSION CHAMBER Filed Feb. 14, 1950 Patented Nov.24, 1953 OFFICE EXHAUST MUFFLER WITH EXPANSION CHAMBER George BromheadWalker, Portarlington, Victoria, Australia Application February 14,1950, Serial No. 144,060

Claims priority, application Australia March 21, 1949 1 Claim.

This invention relates to an improved silencer or muffler intendedmainly for the exhausts of internal combustion engines, 'out suitablealso for other gas exhausts.

The object of the invention is to provide an exhaust gas silencer ormuffler of relatively simple and inexpensive construction which, in use,has low back pressure and otherwise will be found very efficient.

According to the invention, the improved silencer or muiiler has ahollow central member open at one end to receive the exhaust gases andclosed at the other end with ports near to its inlet end to allow thegases to escape to an expansion space. member` functions as a gasaccumulator to smooth out the pulsating pressures of the engine exhaust,the gas pressure accumulating in said closed end portion on the highpressure phase and being released through the ports on the low vpressure phase.

The expansion space is of annular form preferably formed by a taperingcasing surrounding the hollow central member. rThe space thus formedprogressively increases in area from the inlet to the outlet so that thesmoothed out gases escaping from the ports of the hollow central memberare caused to expand as they traverse the expansion space and are thusconsiderably reduced in pressure in addition to being substantially freefrom pulsations when they reach the outlet.

The invention is more fully described aided by reference to theaccompanying drawings where- Fig. l is a longitudinal sectional view ofthe improved silencer or muffler.

Fig. 2 is a cross-section taken on the line 2 2 and Fig. 3 across-section on the line 3-3 of Fig. 1.

Fig. 4 is a detail View of the supporting ring or spider for the hollowcentral member.

As is shown in these views, the silencer or muffler comprises the hollowcylindenlike central member I fitted within a casing 2 of taperingformation increasing in diameter from the inlet end 3 to the outlet endI so as to form the annular expansion space or chamber 5 for the exhaustgases. The cross-sectional area of the expansion space or chamber 5increases progressively from the inlet end to the outlet end.

One end 6 of the hollow central member l is open to the inlet end 3preferably by being driven into said end with a frictional fit as shown.The other end i of said central member is closed.

The closed end portion of the hollow Cil Provided in the central memberI near to its open end 6 are a plurality of gas ports 8 which allow theexhaust gases entering the central member to pass into the expansionspace or chamber 5. Said ports 8 are preferably of elongated form asshown and each has an internal angularly set baille 9 to cause the gasesto enter the expansion space or chamber 5 with a helical or swirlingaction.

Any suitable number of ports 8 may be provided around the circumferenceof the central member and, if desired, a further series of similar portsmay be provided inwardly of the ports 8.

The rear closed end 'l of the central member may be supported in anydesired manner. In the construction shown, said end has a welded-on nutiii receiving a screwed stud Ii supported in a central hole I2 in aspider I3. The spider is supported between a flange I4 on the end of thecasing 2 and a similar iiange I5 on an end member I6 which connects tothe usual exhaust pipe. The stud II also supports a washer I1 and atapered tail I8 which avoids the formation of a low pressure zone in thespace immediately behind the central member l.

In use, the exhaust gases pass into the hollow central member I from theinlet 3 and escape from the latter through the ports 8 into theexpansion space 5 between the central member and the casing 2. The gasesthen pass with a helical or swirling movement aiong said space to theoutlet end and, as the cross-sectional area of said space progressivelyincreases, the exhaust gases expand in their passage and so becomegreatly reduced in pressure on reaching the outlet 4.

The portion I9 of the hollow central member between the ports 8 and theclosed inner end I functions as a gas accumulator and so smoothes outthe pulsating pressures of the exhaust. On the high pressure phase, thegas pressure accumulates in the portion IS and is released through theports 8 on the low pressure phase. Thus, when the gases escape throughthe end member I5 to the exhaust pipe, they are greatly reduced inpressure and substantialiy free from pulsations. Noise is therebypractically eliminated. The swirling motion imparted to the gases by thevanes 9 has the effect of reducing back pressure.

To permit escape of any water that may condense in the silencer, thelower opening in the spider I3 has a downwardly extended portion 20, seeFig. 4, which registers with slots 2i in the flanges I4 and I5. Thepassage formed by the portion 20 and the slots 2| allows watercondensing in the silencer to readily drain away.

What I claim is:

An exhaust silencer for internal combustion engine exhausts, comprisingan elongated outer` casing having coaxially arranged tubular inlet andoutlet connections, a spider mounted in said outer casing in a positionclosely adjacent said outlet connection, an elongated hollow centralmember having one open end 'arranged as a slicling fit within saidtubular inlet connection and the other end closed, a tapered extensionxed to said closed end and engaged by said spider so as to support andcenter said closed end, the portion of said outer casing intermediateIsaid two ends enclosing between itself and said hollow central memberan expansion chamber progressively increasing in area from said inletend to said outlet end, and said hollow central member having elongatedports formed in its side walls and located exclusively in a part thereofsurrounded by the smaller end of the expansion chamber.

GEORGE BROMHEAD WALKER,

References Cited in the file of this Vpatent UNITED STATES PATENTSNumber Name Date 753,845 Brockway Mar. 8, 1904 1,157,256 vSchmitt Oct.19, 1915 1,671,829 Ledwinka May 29, 1928 2,075,265 Bourne Mar. 30, 19372,511,597 Marx June 13, 1950 FOREIGN PATENTS Number` Country Date '9,297Great Britain Apr. 22, 1907 of 1907 v701,684 France Jan. 12, 1931563,018 Germany Oct. 31, 1932 487,816 Great Britain Y June 27, 1938

